The present invention relates generally to yarns, fabrics and protective garments knitted of such yarns. More particularly, the present invention relates to a lightweight cut-resistant composite yarn construction that provides effective cut resistance for a protective garment without sacrificing the comfort and tactile sensitivity of the wearer.
In many industries, it is desirable to provide protective garments, particularly gloves, to protect employees from being cut. Ideally, such garments should provide an acceptable amount of cut resistance while possessing suitable flexibility and durability. To this point knit garments having these qualities have been constructed with constituents of wire or high performance fibers. xe2x80x9cCut resistance,xe2x80x9d as used herein, refers to the ability to prevent laceration or puncture of the garment by sharp objects such as knives. High performance fibers include SPECTRA(copyright), KEVLAR(copyright), and CERTRAN(copyright). To date, composite cut-resistant yarns have been constructed using a wrapping technique wherein a core of single or multiple strands is wrapped with one or more additional strands. Either the core or the wrap strands may include strands comprised of cut-resistant material.
In addition to their higher costs, the use of high performance fibers alone in the core or wrap strands to make cut-resistant composite yarns and garments have not come without certain disadvantages. Articles made from these high performance fibers may be stiff and bulky, particularly in the case of protective gloves, and cause the wearer to fatigue more quickly with an attendant loss of tactile sensation. This is due in large part to the higher weight per unit length, or denier, of the high-performance fibers used to achieve an acceptable level of cut resistance. Such lose of sensitivity can create a hazardous situation. for workers in industries such as meat packing.
Responsive to the disadvantages created with yarn constructions solely utilizing high performance core and/or wrap strands for cut-resistance, cut-resistant yarns in which one or more wire strands are wrapped around a core of soft, conventional material such as fiberglass have been developed. While these yarns have proven more flexible, and to some extent less expensive, than those formed solely from high performance constituents, using wire to form yarn has also proven problematic. Specifically, when knitting with such yarn, unprotected or unshielded wire easily becomes knotted and kinked, or otherwise damaged. While not materially altering the fabric structure of the finished glove or other garment, garments formed from the fabric have proven quite uncomfortable to the wearers despite the use of softer fiberglass constituents in the yarn.
The present invention relates to a composite cut-resistant yarn that includes a lightweight core, a sheath, and a wrap. An object of the present invention is to provide a composite yarn that maximizes the advantages of both high performance fibers and wire in a single construction, while substantially reducing the inherent problems when either constituent is used separately. As such, another object of the present invention is to effectively reduce wire damage, weight, and stiffness in the composite yarn.
The core of the present invention includes at least one lightweight fiberglass strand in combination with at least one strand of wire. The wire may be twisted with or wrapped around the fiberglass strand, but is desirably placed in parallel with the fiberglass strand so that bending and twisting of the wire is minimized. While wire used alone as a core produces a stiff and hard hand, this is offset by the use of the softer fiberglass as a cushion strand. For this lightweight yarn, a single fiberglass strand is desirably about 100 denier, but may be up to 600 denier depending on the particular application. For strength, cut-resistance, and corrosion resistance, the core strand of wire is typically formed of annealed stainless steel with a diameter between about 0.0016 and 0.0020 inches, and desirably 0.0016 inches.
At least one sheath strand of high performance yarn, such as SPECTRA(copyright), is wrapped around the fiberglass and wire core at between about 4 and 12 turns per inch. In the preferred embodiment, the high performance sheath strand is 200 to 215 denier; however, a sheath strand of up to 375 denier has been found to substantially improve the cut-resistance of the yarn, while significantly eliminating the knotting and kinking problems inherent in a construction using only wire. Chiefly, however, the combination of wire and high performance yarn enables a lightweight yarn construction with cut resistance rivaling that of significantly heavier constructions.
The lightweight yarn further includes at least one non-metallic, non-high performance cover strand of a more conventional material wrapped around the core and the sheath. This cover is preferably formed of polyester because of the low shrinkage characteristics of polyester; however, nylon, acrylic, polyester/cotton blend, cotton, or wool are also suitable alternatives. Where a single cover strand is used, a polyester with a denier up to about 200 provides the desired results, with 100 denier being preferred. Desirably, a second non-metallic, non-high performance cover strand is wrapped around the first cover in a direction opposite that of the first cover strand. While one cover is adequate in providing a soft hand in this construction, a second cover provides extra softness, albeit a slightly heavier yarn.
A variety of gloves, sleeves, and other cut-resistant products may be formed from the lightweight yarn of the present invention. Because a variety of yarn deniers and wire sizes may be used in forming the cut-resistant yarn described herein, the yarn may be used on knitting machines with gauges between 7 and 15.
These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the preferred embodiments when considered in conjunction with the drawings. It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.